Reports have shown that HIV (+) substance abusing individuals are at greater risk of having cognitive and psychiatric disorders than the general population. The present study will examine psychosocial and cognitive variables present among individuals who are substance abusers infected with HIV, but still asymptomatic compared with non-infected substance abusers. This is a retrospective case-control study of individuals who have been tested for HIV antibody prior to participating in protocols at the ARC and to whom a psychological assessment battery has been administered during the intake process. The cases will be HIV (+) subjects who will be matched with a corresponding HIV (-) control. Matching will be done by: 1) illicit drug of choice; 2) age (+/-) 6 years; 3) gender; 4) ethnic group; and 5) date of psychological testing (+/-) 3 months. Analysis of psychosocial and cognitive variables will be made primarily based on the results of the Shipley Institute of Living Scale, Addiction Severity Index, and Symptom Checklist -90 Revised. For the sub-population of subjects who participated in treatment studies, retention time in treatment and the results of the urine toxicology tests will be analyzed as treatment outcome measures for each group. Sixty-five cases in each group were identified. Preliminary analysis indicates no significant differences between asymptomatic HIV + and HIV - drug abusers on cognitive function or psychological condition (except for phobic anxiety on SCL-90R).